Numerical thermal performance analysis in a heat exchanger tube with V-shaped discrete ribs

Abstract

This paper presents a numerical investigation on thermal and flow behaviors in a heat exchanger tube fitted with three pairs of 45 deg. V-shaped discrete ribs (VDR) placed repeatedly along the tube wall. Air employed as the test fluid flows into the isothermal ribbed tube for Reynolds numbers (Re) between 3000 and 20,000. The finite volume method was applied for the computations whereas the SIMPLE algorithm was employed for handling the pressurevelocity coupling. This study shows that there are three pairs of counterrotating vortices that can induce reattachment flows on the ribs and its vicinity resulting in greater increase in thermal performance. Moreover, influences of relative rib height (e/D) and pitch (PR=P/D) on heat transfer behaviors are reported. The investigation reveals that the increment of e/D results in the increasing rate of heat transfer and pressure loss while the rise of PR gives the reversing trend. The use of VDR yields very high thermal performance compared with the smooth tube.